Alzheimer's disease (AD) is a neurodegenerative disease pathologically characterized by the accumulation of intracellular neurofibrillary tangles and extracellular deposition of amyloid fibrils. The principal component of the amyloid fibrils is the beta-amyloid (A.beta.) peptide, which is derived from the amyloid precursor protein (APP). Drugs that prevent or retard assembly of the A.beta. peptide into amyloid fibrils without non-specific disruption of protein--protein interactions are thought to arrest or slow the neurodegeneration and progressive cognitive decline in patients with AD by blocking amyloid plaque deposition.
This invention is directed to a novel isochroman compound and a salt thereof which is useful as an A.beta. protein aggregation inhibitor and for treating Alzheimer's disease, and pharmaceutical compositions of the compound. Another object of the present invention is to provide processes for producing the isochroman compound.
C. J. Pike et al. suggest that the A.beta. protein aggregation inhibitor is useful for treating Alzheimer's disease (European Journal of Pharmacology--Molecular Pharmacology Section, Vol. 207, pp. 367-368, 1991).